I bought a $ 25 gift card code has been sent to me, please apply

Hi Lid es,
I understand that you would like to redeem your iTunes Gift card that you purchased. That is something that I can help you out with.
All you need to do is locate the code on your gift card and then navigate to the Redeem page. Then it is a matter of entering in the code and signing in with your Apple ID and it will be linked to your account. Take a look at the information below for more details.
Redeem iTunes Gift Cards and codes
https://support.apple.com/en-us/HT201209
Have a good day